由美国国立卫生研究院资助 R01 EY035278 （MR） 支持。

猪的眼睛是从当地的屠宰场获得的。不需要伦理委员会的批准。
1.晶状体解剖（图1）
<ol><li>从猪眼中去除所有周围组织，从巩膜中去除多余的肉，直到只剩下视神经。使用弯曲的镊子和小解剖剪刀完成此过程。在解剖过程中使用神经作为锚来固定眼睛。</li>
	<li>使用手术刀在角膜缘做一个短的圆周切口，然后在赤道处再做一个切口。 注意： 按此顺序执行此步骤以避免损坏镜头和胶囊。</li>
	<li>将显微剪刀插入角膜缘处的切口，并用细钝头镊子提起角膜，同时绕角膜圆周切割，取出角膜。</li>
	<li>使用钝头镊子抬起去除虹膜，然后用微型剪刀剪掉。</li>
	<li>将解剖剪刀插入赤道切口，然后围绕整个赤道圆周切割，直到巩膜一分为二。</li>
	<li>切口完成后，切除巩膜的后部。用镊子轻轻取出玻璃体，留下最少的残留物，以免损坏晶状体。如果需要，切开玻璃体，使后体远离晶状体和前节。</li>
	<li>使用显微剪刀从前到后在巩膜上做一个经向切口。</li>
	<li>从穿过巩膜的新经线切口开始，使用显微剪刀将小带从晶状体上切开。利用晶状体的重量或解剖盘的边缘，在将晶状体和巩膜稍微分开时轻轻拉伸小带，让显微剪刀在小晶状体和睫状体之间、穿过小带和圆锥体周围切割。如果操作正确，这将隔离镜头而不会损坏镜头胶囊。</li>
	<li>如果需要，使用镊子取出胶囊，在赤道处刺穿胶囊，然后用两把镊子剥离胶囊。</li>
	<li>将镜头放入磷酸盐缓冲盐水 （PBS） 中。在进行机械测试之前，目视检查镜头是否有任何损坏。</li>
</ol>2. 带/不带透镜囊的镜头压缩（图 2）
注意：除步骤 2.1 和 2.4 外，此处的所有步骤均由计算机控制。
<ol><li>获得或构建具有 50 克力容量称重传感器的平行板压缩装置，能够测量 1 μm 量级的位移。</li>
	<li>对电动载物台进行编程并加载单元以执行下面描述的加载方案（例如， 补充文件 1）。</li>
	<li>用 PBS 几乎填充一个 1 5/8 英寸 x 1 5/8 英寸的方形盒子，并将其放在压缩平台上。</li>
	<li>将上板降低到与下板接触的位置，以确定运动的下限和绝对间隙高度。</li>
	<li>将上板抬高 ~15 毫米。</li>
	<li>将镜头放在盒子的中心，注意赤道平面是水平的。</li>
	<li>降低靠近镜头上表面但不与镜片上表面接触的上板。</li>
	<li>使用接触阈值为 3 mN 的力反馈启动运动以移动上板与镜头接触。</li>
	<li>在确定接触、记录时间、上板相对于下板的位置以及 500 Hz 的力后开始数据记录。</li>
	<li>应用预处理负载，其中镜头以 1%/s 的速率压缩其初始高度的 2.5% 三次，然后压缩 5% 三次，然后压缩 7.5% 三次。</li>
	<li>预处理后保持上板位置恒定1分钟。</li>
	<li>以 1%/s 的速率施加 15% 的压缩，然后以相同的速率卸载。</li>
	<li>继续卸载运动，直到上板从底板上移动了另外 2% 的卸载透镜厚度，以确保透镜与上板脱粘。</li>
</ol>3. 透镜模量的估算
<ol><li>根据仪器在接触点的间隙估计镜头的厚度。或者，使用图像分析来测量测试前拍摄的照片的厚度。</li>
	<li>使用赫兹模型计算弹性模量 E ，用于平行板之间球体的压缩（公式 [1]; 补充文件2）。 <img alt="Equation 1" src="/files/ftp_upload/66040/66040eq01.jpg" style="margin: auto;">（一） 其中 R 是接触点的曲率半径（假设等于透镜厚度的一半）; F 是称重传感器报告的压缩力; <img alt="Equation 2" src="/files/ftp_upload/66040/66040eq02.jpg" style="margin: auto;"> 是泊松比（假设等于0.5，对应于不可压缩材料）; u 是上级从接触点向下接近。请注意，弹性模量和泊松比是材料属性，分别表示透镜的固有刚度和透镜的相对压缩性。 注意：这种方法忽略了晶状体胶囊的任何作用，但大致考虑了晶状体的尺寸，允许物种之间的比较。</li>
</ol>

自动压缩猪晶状体的生物力学表征

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作者没有利益冲突需要声明。

镜片压缩是一种用于估计镜片刚度的通用方法。上述程序允许比较不同物种和不同尺寸的镜片。所有变形都根据透镜尺寸进行归一化，弹性模量的计算大致考虑透镜尺寸。有效模量远高于之前报道的猪透镜4、7、11、19 的模量，至少部分原因是使用了厚度而不是曲率半径：猪透镜的极曲半径明显大于厚...

晶状体是眼睛中发现的透明且灵活的器官，它可以通过改变屈光度来聚焦在不同的距离上。这种能力被称为适应。由于睫状肌的收缩和松弛，屈光力会改变。当睫状肌收缩时，晶状体增厚并向前移动，增加其屈光力1,2。屈光率的增加使镜头能够聚焦在附近的物体上。随着人类年龄的增长，晶状体会变得更硬，这种适应能力会逐渐丧失;这种情况被称为老花眼。变硬的机制仍然未知，至少部分原因是与晶状体的生物力学表征相关的困难。
已经采用了多种方法来估计晶状体刚度和生物力学性能。这些方法包括透镜旋转3,4,5，声学方法6,7,8，光学方法，如布里渊显微镜9，压痕10,11和压缩12,13。压缩是最容易获得的实验技术，因为它可以使用简单的仪器（例如，玻璃盖玻片14,15）或单个电动载物台进行。我们之前已经展示了如何从压缩测试中严格估计晶状体的生物力学特性16.这个过程在技术上具有挑战性，需要专门的软件，而对相对刚度测量感兴趣的镜头研究人员不容易使用。因此，在本研究中，我们专注于在考虑透镜尺寸的同时估计透镜弹性模量的可用方法。弹性模量是与其变形性相关的固有材料特性：高弹性模量对应于较硬的材料。
该测试本身是平行板压缩测试，因此可以在合适的商业机械测试系统上进行。在这里，构建了一个由电机、线性平台、运动控制器、称重传感器和放大器组成的定制仪器。这些都是使用定制软件控制的，该软件还定期记录时间、位置和负载。猪镜片不适应，但易于获得且价格低廉17.开发了以下方法来逐步压缩眼睛晶状体并量化其弹性模量。这种方法可以很容易地复制，并且在晶状体刚度的研究中很有用。

<table><tbody><tr><td>Curved Medium Point General Purpose Forceps</td><td>Fisherbrand</td><td>16-100-110</td><td></td></tr><tr><td>Galil COM Libraries</td><td>Galil Motion Control</td><td></td><td></td></tr><tr><td>High Precision Scalpel Handle&amp;nbsp;</td><td>Fisherbrand</td><td>12-000-164</td><td></td></tr><tr><td>Linear Stage</td><td>McMaster-Carr</td><td>6734K4 0.125&quot;</td><td></td></tr><tr><td>Load Cell</td><td>FUTEK</td><td>LSB200-FSH03869</td><td></td></tr><tr><td>Load Cell Amplifier</td><td>FUTEK</td><td>IAA300-FSH03931</td><td></td></tr><tr><td>MATLAB</td><td>The Mathworks, Inc.</td><td></td><td></td></tr><tr><td>Microprobe</td><td>Surgical Design&amp;nbsp;</td><td>22-079-740</td><td></td></tr><tr><td>Miniature Self Opening Precision Scissors&amp;nbsp;</td><td>Excelta&amp;nbsp;</td><td>63042-004</td><td></td></tr><tr><td>Motion Controller</td><td>Galil Motion Control</td><td>DMC-31012</td><td></td></tr><tr><td>Motor</td><td>Galil Motion Control</td><td>BLM-N23-50-1000-B</td><td></td></tr><tr><td>Straight Hemastats&amp;nbsp;</td><td>Fine Science&amp;nbsp;</td><td>NC9247203</td><td>stainless steel, 14cm&amp;nbsp;</td></tr></tbody></table>

automated compression testing of the ocular lens

人工晶状体的生物力学特性对于其作为可变功率光学元件的功能至关重要。这些特性随着人类晶状体年龄的增长而发生巨大变化，导致近视力丧失，称为老花眼。然而，这些变化的机制仍然未知。晶状体压缩提供了一种相对简单的方法，用于定性地评估晶状体的生物力学刚度，并且当与适当的分析技术相结合时，可以帮助量化生物力学特性。迄今为止，已经进行了各种镜片压缩测试，包括手动和自动，但这些方法应用生物力学测试的关键方面不一致，例如预处理、加载速率和测量间隔时间。本文描述了一种全自动镜头压缩测试，其中电动载物台与相机同步，以在整个预编程的加载协议中捕获镜头的力、位移和形状。然后可以从这些数据中计算出特征弹性模量。虽然这里使用猪镜片进行演示，但该方法适用于任何物种的镜片压缩。

压缩六个猪晶状体，首先在胶囊完好无损的情况下，然后在小心地取出胶囊后。封装镜片的厚度值分别为 7.65 ± 0.43 mm，解封镜片的厚度值分别为 6.69 ± 0.29 mm（平均值±标准差）。典型的加载历史记录如 图 3 所示。赫兹模型很好地拟合了由此产生的力-位移曲线（即，它们的力与升至1.5次方的位移成正比; 图4）。封装和解封膜透镜都是如此。
<p class="j...

Watch this Scientific Journal Video about Advancing Understanding of Age-Related Lens Stiffness Changes at JoVE.com

作者聚焦：增进对与年龄相关的晶状体僵硬变化的理解 

我们提出了一种使用压缩测试表征人工晶状体有效弹性模量的自动化方法。

人工晶状体的自动压缩测试

The biomechanical properties of the ocular lens are essential to its function as a variable power optical element. These properties change dramatically ...

我们试图了解人们如何随着年龄的增长而失去近视力。我们知道这在一定程度上是由于晶状体刚度的变化，但我们仍然不知道为什么晶状体会随着年龄的增长而变硬。目前的实验方法依赖于粗略的方法来加载镜头，例如在镜头上放置显微镜盖玻片。这些方法很繁琐，并且缺乏对加载速率的适当控制。我们已经确定晶状体形状是老花眼的主要驱动因素，并且我们知道形状主要由生物力学参数驱动。该协议为测量透镜刚度提供了一种完全客观、可重复的方法。自动化使我们能够控制加载速率，这是表征粘弹性材料（如透镜）时的关键参数。我们现在有一个客观的、可重复的协议来测量晶状体的生物力学特性。这将使我们能够严格表征晶状体如何随着年龄的增长而变硬，以及特定蛋白质如何改变晶状体的生物力学特性。

automated-compression-testing-of-the-ocular-lens

Universidad de Cartagena UDEC

Research

JoVE Journal

Bioengineering

Automated Compression Testing of the Ocular Lens

2.2K 次观看.  The Ohio State University. 我们试图了解人们如何随着年龄的增长而失去近视力。我们知道这在一定程度上是由于晶状体刚度的变化，但我们仍然不知道为什么晶状体会随着年龄的增长而变硬。目前的实验方法依赖于粗略的方法来加载镜头，例如在镜头上放置显微镜盖玻片。这些方法很繁琐，并且缺乏对加载速率的适当控制。我们已经确定晶状体形状是老花眼的主要驱动因素，并且我们知道形状?...

视频: 作者聚焦：增进对与年龄相关的晶状体僵硬变化的理解 

Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application

This study discusses a synthesis route for soft polysiloxane-based urea (PSU) elastomers for their applications as accommodating intraocular lenses (a-IOLs). Aminopropyl-terminated polydimethylsiloxanes (PDMS) were previously prepared via the ring-chain equilibration of the cyclic siloxane octamethylcyclotetrasiloxane (D4) and 1,3-bis(3-aminopropyl)-tetramethyldisiloxane (APTMDS). Phenyl groups were introduced into the siloxane backbone via the copolymerization of D4 and 2,4,6,8-tetramethyl-2,4,6,8-tetraphenyl-cyclotetrasiloxane (D4Me,Ph). These polydimethyl-methyl-phenyl-siloxane-block copolymers were synthesized for increasing the refractive indices of polysiloxanes. For applications as an a-IOL, the refractive index of the polysiloxanes must be equivalent to that of a young human eye lens. The polysiloxane molecular weight is controlled by the ratio of the cyclic siloxane to the endblocker APTMDS. The transparency of the PSU elastomers is examined by the transmittance measurement of films between 200 and 750 nm, using a UV-Vis spectrophotometer. Transmittance values at 750 nm (upper end of the visible spectrum) are plotted against the PDMS molecular weight, and &#62; 90% of the transmittance is observed until a molecular weight of 18,000 g&#183;mol&#8722;1. Mechanical properties of the PSU elastomers are investigated using stress-strain tests on die-cut dog-bone-shaped specimens. For evaluating mechanical stability, mechanical hysteresis is measured by repeatedly stretching (10x) the specimens to 5% and 100% elongation. Hysteresis considerably decreases with the increase in the PDMS molecular weight. In vitro cytotoxicity of some selected PSU elastomers is evaluated using an MTS cell viability assay. The methods described herein permit the synthesis of a soft, transparent, and noncytotoxic PSU elastomer with a refractive index approximately equal to that of a young human eye lens.

This study describes synthetic routes for aminopropyl-terminated polydimethylsiloxanes and polydimethyl-methyl-phenyl-siloxane-block copolymers and for soft polysiloxane-based urea (PSU) elastomers. It presents the application of PSUs as accommodating an intraocular lens. An evaluation method for in vitro cytotoxicity is also described.

软聚聚硅氧烷-尿素弹性体在人工晶体中的应用

This study discusses a synthesis route for soft polysiloxane-based urea (PSU) elastomers for their applications as accommodating intraocular lenses ...

科研

化学

Development of an In Vitro Ocular Platform to Test Contact Lenses

Currently, in vitro evaluations of contact lenses (CLs) for drug delivery are typically performed in large volume vials,1-6 which fail to mimic physiological tear volumes.7 The traditional model also lacks the natural tear flow component and the blinking reflex, both of which are defining factors of the ocular environment. The development of a novel model is described in this study, which consists of a unique 2-piece design, eyeball and eyelid piece, capable of mimicking physiological tear volume. The models are created from 3-D printed molds (Polytetrafluoroethylene or Teflon molds), which can be used to generate eye models from various polymers, such as polydimethylsiloxane (PDMS) and agar. Further modifications to the eye pieces, such as the integration of an explanted human or animal cornea or human corneal construct, will permit for more complex in vitro ocular studies. A commercial microfluidic syringe pump is integrated with the platform to emulate physiological tear secretion. Air exposure and mechanical wear are achieved using two mechanical actuators, of which one moves the eyelid piece laterally, and the other moves the eyeballeyepiece circularly. The model has been used to evaluate CLs for drug delivery and deposition of tear components on CLs.

Development of an In Vitro Ocular Platform to Test Contact Lenses

Current in vitro models for evaluating contact lenses (CLs) and other eye-related applications are severely limited. The presented ocular platform simulates physiological tear flow, tear volume, air exposure and mechanical wear. This system is highly versatile and can be applied to various in vitro analyses with CLs.

的发展<em&gt;体外</em&gt;眼平台，试验用隐形眼镜

Currently, in vitro evaluations of contact lenses (CLs) for drug delivery are typically performed in large volume vials,1-6 which fail to mimic ...

生物工程

Trabecular Meshwork Response to Pressure Elevation in the Living Human Eye

The mechanical characteristics of the trabecular meshwork (TM) are linked to outflow resistance and intraocular pressure (IOP) regulation. The rationale behind this technique is the direct observation of the mechanical response of the TM to acute IOP elevation. Prior to scanning, IOP is measured at baseline and during IOP elevation. The limbus is scanned by spectral-domain optical coherence tomography at baseline and during IOP elevation (ophthalmodynamometer (ODM) applied at 30 g force). Scans are processed to enhance visualization of the aqueous humor outflow pathway using ImageJ. Vascular landmarks are used to identify corresponding locations in baseline and IOP elevation scan volumes. Schlemm canal (SC) cross-sectional area (SC-CSA) and SC length from anterior to posterior along its long axis are measured manually at 10 locations within a 1 mm segment of SC. Mean inner to outer wall distance (short axis length) is calculated as the area of SC divided by its long axis length. To examine the contribution of adjacent tissues to the effect IOP elevations, measurements are repeated without and with smooth muscle relaxation with instillation of tropicamide. TM migration into SC is resisted by TM stiffness, but is enhanced by the support of its attachment to adjacent smooth muscle within the ciliary body. This technique is the first to measure the living human TM response to pressure elevation in situ under physiological conditions within the human eye.

Trabecular meshwork (TM) migration into Schlemm&#8217;s canal space can be induced by acute pressure elevation by ophthalmodynamometer, and observed by spectral domain optical coherence tomography. The goal of this method is to quantify the morphometric response of the living outflow tract to acute pressure elevation in living tissues in situ.

小梁响应压升高在活的人类眼睛

The mechanical characteristics of the trabecular meshwork (TM) are linked to outflow resistance and intraocular pressure (IOP) regulation. The rationale ...

医学

Simulating the Mechanics of Lens Accommodation via a Manual Lens Stretcher

The goal of this protocol is to mimic the biomechanics of physiological accommodation in a cost-efficient, practical manner. Accommodation is achieved through the contraction of the ciliary body and relaxation of zonule fibers, which results in the thickening of the lens necessary for near vision. Here, we present a novel, simple method in which accommodation is replicated by tensing the zonules connected to the lens capsule via a manual lens stretcher (MLS). This method monitors the radial stretching achieved by a lens when subjected to a consistent force and allows for a comparison of accommodating lenses, which can be stretched, to non-accommodating lenses, which cannot be stretched. Importantly, the stretcher couples to the zonules directly, and not to the sclera of the eye, thus only requiring the lens, zonules, and ciliary body rather than the entire globe sample. This difference can significantly decrease the cost of acquiring donor cadaver lenses by about 62% compared to acquiring an entire globe.

We present an efficient method of studying lens accommodation by using a manual lens stretcher. The protocol mimics physiological accommodation by pulling the zonules connected around the lens capsule, thereby, stretching the lens.

用人工晶状体担架模拟透镜体的力学性能

The goal of this protocol is to mimic the biomechanics of physiological accommodation in a cost-efficient, practical manner. Accommodation is achieved ...

In vivo Structural Assessments of Ocular Disease in Rodent Models using Optical Coherence Tomography

Spectral-domain optical coherence tomography (SD-OCT) is useful for visualizing retinal and ocular structures in vivo. In research, SD-OCT is a valuable tool to evaluate and characterize changes in a variety of retinal and ocular disease and injury models. In light induced retinal degeneration models, SD-OCT can be used to track thinning of the photoreceptor layer over time. In glaucoma models, SD-OCT can be used to monitor decreased retinal nerve fiber layer and total retinal thickness and to observe optic nerve cupping after inducing ocular hypertension. In diabetic rodents, SD-OCT has helped researchers observe decreased total retinal thickness as well as decreased thickness of specific retinal layers, particularly the retinal nerve fiber layer with disease progression. In mouse models of myopia, SD-OCT can be used to evaluate axial parameters, such as axial length changes. Advantages of SD-OCT include in vivo imaging of ocular structures, the ability to quantitatively track changes in ocular dimensions over time, and its rapid scanning speed and high resolution. Here, we detail the methods of SD-OCT and show examples of its use in our laboratory in models of retinal degeneration, glaucoma, diabetic retinopathy, and myopia. Methods include anesthesia, SD-OCT imaging, and processing of the images for thickness measurements.

Here, we describe the use of spectral-domain optical coherence tomography (SD-OCT) to visualize retinal and ocular structures in vivo in models of retinal degeneration, glaucoma, diabetic retinopathy, and myopia.

使用光学相干断层扫描对啮齿动物模型中眼部疾病的体内结构评估

Spectral-domain optical coherence tomography (SD-OCT) is useful for visualizing retinal and ocular structures in vivo. In research, SD-OCT is a valuable ...

Anterior Segment Organ Culture Platform for Tracking Open Globe Injuries and Therapeutic Performance

Open globe injuries have poor visual outcomes, often resulting in permanent loss of vision. This is partly due to an extended delay between injury and medical intervention in rural environments and military medicine applications where ophthalmic care is not readily available. Untreated injuries are susceptible to infection after the eye has lost its watertight seal, as well as loss of tissue viability due to intraocular hypotension. Therapeutics to temporarily seal open globe injuries, if properly developed, may be able to restore intraocular pressure and prevent infection until proper ophthalmic care is possible. To facilitate product development, detailed here is the use of an anterior segment organ culture open globe injury platform for tracking therapeutic performance for at least 72 h post-injury. Porcine anterior segment tissue can be maintained in custom-designed organ culture dishes and held at physiological intraocular pressure. Puncture injuries can be created with a pneumatic-powered system capable of generating injury sizes up to 4.5 mm in diameter, similar to military-relevant injury sizes. Loss of intraocular pressure can be observed for 72 h post-injury confirming proper injury induction and loss of the eye&#39;s watertight seal. Therapeutic performance can be tracked by application to the eye after injury induction and then tracking intraocular pressure for multiple days. Further, the anterior segment injury model is applicable to widely used methods for functionally and biologically tracking anterior segment physiology, such as assessing transparency, ocular mechanics, corneal epithelium health, and tissue viability. Overall, the method described here is a necessary next step toward developing biomaterial therapeutics for temporarily sealing open globe injuries when ophthalmic care is not readily available.

Open globe eye injuries may go untreated for multiple days in rural or military-relevant scenarios, resulting in blindness. Therapeutics are needed to minimize loss of vision. Here, we detail an organ culture open globe injury model. With this model, potential therapeutics for stabilizing these injuries can be properly evaluated.

跟踪开放全球伤害和治疗性能的前段器官文化平台

Open globe injuries have poor visual outcomes, often resulting in permanent loss of vision. This is partly due to an extended delay between injury and ...

Using an Automated Hirschberg Test App to Evaluate Ocular Alignment

A smartphone app has been developed to perform the automated photographic Hirschberg test for objective measurement of ocular misalignment. By computing the difference in corneal reflection generated by the phone camera flash relative to the iris center based on high resolution images, the app can measure misalignment with a much higher precision than the naked eye performing the Hirschberg test. It has been validated in a previous clinical evaluation study by comparing to the clinical gold standard-prism and alternate cover test. The goal of this article is to describe the testing techniques regarding how to use the app to measure ocular alignment for different fixation distances, without or with cover to break fusion, as well as angle kappa, so that users can use the app to perform equivalent tests typically done in clinic using prisms.

We present a protocol of using a smartphone app to perform Hirschberg test for measuring manifest and intermittent ocular misalignment (strabismus) under near and far fixation conditions.

使用自动赫希伯格测试应用程序评估眼部对齐

A smartphone app has been developed to perform the automated photographic Hirschberg test for objective measurement of ocular misalignment. By computing ...

Sequential Application of Glass Coverslips to Assess the Compressive Stiffness of the Mouse Lens: Strain and Morphometric Analyses

The eye lens is a transparent organ that refracts and focuses light to form a clear image on the retina. In humans, ciliary muscles contract to deform the lens, leading to an increase in the lens&#39; optical power to focus on nearby objects, a process known as accommodation. Age-related changes in lens stiffness have been linked to presbyopia, a reduction in the lens&#39; ability to accommodate, and, by extension, the need for reading glasses. Even though mouse lenses do not accommodate or develop presbyopia, mouse models can provide an invaluable genetic tool for understanding lens pathologies, and the accelerated aging observed in mice enables the study of age-related changes in the lens. This protocol demonstrates a simple, precise, and cost-effective method for determining mouse lens stiffness, using glass coverslips to apply sequentially increasing compressive loads onto the lens. Representative data confirm that mouse lenses become stiffer with age, like human lenses. This method is highly reproducible and can potentially be scaled up to mechanically test lenses from larger animals.

Age-related increases in eye lens stiffness are linked to presbyopia. This protocol describes a simple, cost-effective method for measuring mouse lens stiffness. Mouse lenses, like human lenses, become stiffer with age. This method is precise and can be adapted for lenses from larger animals.

盖玻片序贯应用评估鼠标透镜的抗压刚度:应变和形态分析

The eye lens is a transparent organ that refracts and focuses light to form a clear image on the retina. In humans, ciliary muscles contract to deform the ...

生物学

Binocular Dynamic Visual Acuity in Eyeglass-Corrected Myopic Patients

Current clinical visual assessment mainly focuses on static vision. However, static vision may not sufficiently reflect real-life visual function as moving optotypes are frequently observed daily. Dynamic visual acuity (DVA) might reflect real-life situations better, especially when objects are moving at high speeds. Myopia impacts static uncorrected distance visual acuity, conveniently corrected with eyeglasses. However, due to peripheral defocus and prism effects, eyeglass correction might affect DVA. The present research demonstrates a standard method to examine eyeglass-corrected DVA in myopia patients, and aimed to explore the influence of eyeglass correction on DVA. 
Initially, standard subjective refraction was performed to provide the eyeglass prescription to correct the refractive error. Then, binocular distance vision-corrected DVA was examined using the object-moving DVA protocol. Software was designed to display the moving optotypes according to the preset velocity and size on a screen. The optotype was the standard logarithmic visual chart letter E and moves from the middle of the left to the right side horizontally during the test. Moving optotypes with randomized opening direction for each size are displayed. The subjects were required to identify the opening direction of the optotype, and the DVA is defined as the minimum optotype that subjects could recognize, calculated according to the algorithm of logarithmic visual acuity.
Then, the method was applied in 181 young myopic subjects with eyeglass-corrected-to-normal static visual acuity. Dominant eye, cycloplegic subjective refraction (sphere and cylinder), accommodation function (negative and positive relative accommodation, binocular cross-cylinder), and binocular DVA at 40 and 80 degrees per second (dps) were examined. The results showed that with increasing age, DVA first increased and then decreased. When myopia was fully corrected with eyeglasses, a worse binocular DVA was associated with more significant myopic refractive error. There was no correlation between the dominant eye, accommodation function, and binocular DVA.

The present research demonstrates a method to accurately examine dynamic visual acuity (DVA) in myopic subjects with eyeglass correction. Further analysis indicated that the closer the refraction state to emmetropia, the better the eyeglass-corrected binocular DVA is at both 40 and 80 degrees per second.

眼镜矫正近视患者的双眼动态视力

Current clinical visual assessment mainly focuses on static vision. However, static vision may not sufficiently reflect real-life visual function as ...

Organ Culture System for Assessing the Toxicity of Intraocular Treatment Excipients and Pharmaceuticals

As the leading cause of blindness, cataracts are a significant burden for the tens of millions of people affected globally by this condition. Chemical exposures, among other environmental factors, are an established cause of cataracts. Ocular toxicity testing can assess whether pharmaceuticals and their components may contribute to lens damage that may lead to cataracts or aid the treatment of cataracts. 
In vitro studies and in vivo animal testing can be used for assessing the safety of chemicals prior to clinical studies. The Draize test-the current in vivo standard for ocular toxicity and irritancy testing-has been criticized for lack of sensitivity and objective measurements of determining ocular toxicity. In vitro cell-based assays are limited as cell cultures cannot appropriately model an intact functional lens. 
The method described here is a sensitive in vitro alternative to animal testing, designed to evaluate the response of the intact bovine lens to treatment at both the cellular activity level and for overall refractive performance. The non-toxic reagent resazurin is metabolized in proportion to the level of cell activity. The lens laser-scanner assay measures the ability of the lens to refract incident beams of light to a single point with minimal error, directly relevant to its natural function. The method may be used to determine both acute and delayed changes in the lens, as well as the recovery of the lens from chemical or environmental exposures.

The goal of this protocol is to evaluate changes in metabolic activity and refractive function of the lens in response to experimental treatment.

As the leading cause of blindness, cataracts are a significant burden for the tens of millions of people affected globally by this condition. Chemical ...